How to Use OS level monitoring utilities such as TOPAs , iostat , netstat and swap.
AS a DBA,it's very difficult to understand.
Please anyone provide step by step approach for that.When to start & Where to look.
Your question is understandable, but I'm afraid a forum is not a substitute for training or doing some research on your own. People have written books about Linux performance troubleshooting and there are numerous resources on the Web that should help you to get started. A good start might be the Performance Tuning guide. https://linux.oracle.com/documentation/
As with any monitoring tool, it shows only statistics, but does not determine whether or not any system is configured properly or software configured to work efficiently. A system may allocate all available resources to a given task, which as such does not indicate a bottleneck.